The identities of the victims were not immediately released. The worker who died was pronounced dead at the scene. Two workers, ages 50 and 57, were taken to Northwestern Memorial Hospital and two other workers, ages 39 and 51, were taken to Stroger Hospital. All four were in critical condition, according to the Chicago Fire Department.

At about 1:40 p.m., the Chicago Fire Department tweeted that a still-and-box fire had broken out at the structure. The Chicago Sun-Times reported that the building is The Mart Parc Orleans Self Park at 437 North Orleans Street.